Method of producing ingots, in particular, slab ingots, by electroslag remelting of consumable electrodes

ABSTRACT

This disclosure relates to a method of producing ingots, in particular, slab ingots, by electroslag remelting of consumable electrodes. The method according to the present invention consists in the introduction to a cooled crystallizer of two groups of consumable electrodes, each of said groups comprising one electrode, stationary with respect to the crystallizer, and at least one movable electrode, which helps ensure a high quality of slab ingots produced. This method can be most advantageously used for producing slab ingots intended for direct sheet rolling without the use of powerful cogging means.

United States Patent 8/1946 Hopkins .l l64/252UX FOREIGN PATENTS1,448,656 6/1966 France Primary Examiner.i. Spencer Overholser AssistantExaminer-John E. Roethei Attorney-Holman & Stern I ABSTRACT: Thisdisclosure relates to a method of producing ingots, in particular, slabingots, byelectroslag remeiting of consumable electrodes.

- The method according to the present invention consists in theintroduction to a cooled crystailizer of two groups of consumableelectrodes, each of said groups comprising one electrode, stationarywith respect to the crystallizer, and at least one movable electrode,which helps ensure a high quality of slab ingots produced.

This method can be most advantageously used for producing slab ingotsintended for direct sheet roiling without the use of powerful coggingmeans.

[21] Appl. No. 42,913 [22] Filed June 3, 1970 [4S] Patented Nov. 16,1971 [54] METHOD OF PRODUCING INGOTS, IN

PARTICULAR, SLAB INGOTS, BY ELECTROSLAG REMELTING 0F CONSUMABLEELECTRODES 5 Claims, 2 Drawing Figs.

52 us. Cl 164152, 164/252 [51] Int. Cl B22d 27/02 50 Field of Search164/52, 252

[56] References Cited UNITED STATES PATENTS 1 2,191,478 tH9Rk F""t'rr'":':':""i':

METHOD OF PRODUCING INGO'IS, IN PARTICULAR, SLAB INGOTS, BY ELECTROSLAGREMELTING F CONSUMABLE ELECTRODES The present invention relates to thefield of electrometallurgy and, more particularly, it relates to amethod of production, by electroslag remelting of consumable electrodes,of ingots, in particular, slab ingots intended for direct sheet rolling.

Known in the art is a method of producing slab ingots by electroslagremelting in a cooled crystallizer of two groups of movable consumableelectrodes connected in series to the secondary winding of asingle-phase feeding transformer (cf., Belgian Pats. No. 670,299,priority date 29th Sept., 1965, and No. 707,566, priority date 5th Dec.,1967).

However, when producing slab ingots by the latter known method, possibleburns of the crystallizers are to be avoided resulting from the contactof the crystallizer walls with the movable electrodes which, with theirbuming-off, are fed to the crystallizer, to which end the cross sectionof the consumable electrodes has to be reduced, particularly thedimension thereof corresponding to the narrow face of the slab ingot,and the electrode length increased, which causes difficulties in themanufacture of such electrodes and complicates the design of theequipment.

There is likewise known a method of producing ingots by way ofelectroslag remelting in a cooled crystallizer of stationary consumableelectrodes (cf., Belgian Pat. No. 711,199, priority date 23rd Feb.,1968).

Such a method of producing slab ingots can preclude the possibility ofthe crystallizer burns, provide for a high degree of filling thecrystallizer sectional area and, consequently, for reducing the heightof the plant, however, it is impossible to produce a slab ingot ofconsiderable length due to an excessive increase in the depth of theslag bath by the end of meltmg.

For example, when employing the last-mentioned known method of producinga slab ingot with a l40Xl,500 mm. section and 2 m. long, the minimumpossible rated increment of the depth of the slag bath by the end ofmelting is equal to 360 mm., which is by no means tolerable due to asharp deterioration of the quality of metal in the ingot.

It is an object of the present invention to eliminate theabove-mentioned disadvantages.

The main object of the present invention is to provide a method ofproducing ingots, in particular, slab ingots, by electroslag remeltingof consumable electrodes, whereby the melted metal from the ends ofconsumable electrodes is supplied to the slag bath simultaneously overthe whole crystallizer width, which provides for a high quality of slabingots produced.

In the accomplishment of said object of the invention, in a proposedmethod of producing ingots by way of electroslag remelting in a cooledcrystallizer of two groups of consumable electrodes connected in seriesto the secondary winding of a single-phase transformer, according to theinvention, each group of consumable electrodes is composed of at leastone electrode, stationary with respect to the crystallizer and servingto introduce the main portion of metal to the slab ingot being produced,and at least one movable electrode serving to maintain and regulate themelting process and connected in parallel to the stationary electrode.

It is expedient that the movable consumable electrodes be arranged inthe crystallizer between the stationary electrodes or on the outer sidesof the latter.

In order to reduce the length of the bumt-off portion of the movableelectrodes, it is expedient that the remelting process be carried outwith the addition of small amounts of solid flux to the crystallizer.

For increasing the weight of the slab ingot without increasing thelength of the movable electrodes in the course of remelting it ispossible to repeatedly replace the movable consumable electrodes.

The method carried out in accordance with the present invention helpssuccessfully solve the problem of the invention, features an increasedreliability of electroslag remelting process and provides a possibilityof regulating the process for remelting.

For a better understanding of the method of the invention, presentedhereinbelow is a detailed description of an examplary embodimentthereof, 'due reference being had to the accompanying drawings, wherein:

FIG. 1 shows schematically in plan view a possible arrangement of groupsof consumable electrodes in a cooled crystallizer, and a single-phasetransformer feeding them; and

FIG. 2 illustrates a general view of a plant for electroslag remeltingto produce ingots, in accordance with the method of the invention.

Now, referring to FIGS. 1 and 2, a cooled crystallizer 1 accommodatestwo groups of electrodes, each of said groups comprising a stationaryconsumable electrode 2 and a movable consumable electrode 3. The groupsof consumable electrodes are connected in series to a secondary winding4 of a single-phase feeding transformer 5, the electrodes 2 and 3 ineach group being connected to each other in parallel. in addition, witha view to additional stabilization of the buming-off process of thestationary consumable electrodes 2, the middle point 0 of the secondarywinding 4 of the transformer 5 can be electrically connected to a slabingot 7 being produced (in FIGS. 1 and 2 such connection being shownwith a dashed line). In the embodiment illustrated in FIGS. 1 and 2 themovable electrodes 3 are arranged between the stationary electrodes 2,however, the movable electrodes 3 can be also arranged on the outersides of the stationary electrodes 2. With the buming-off of the movableelectrodes 3, the level of a slag bath 6 is shifted upwards 'so that theends of the stationary electrodes 2 stay immersed to a certain measurein the slag bath 6. When so doing, the greater part of the workingcurrent passes in the circuit of the stationary electrodes 2. Meltedmetal from the ends of the consumable electrodes 2 and 3 is supplied tothe slag bath 6 simultaneously over the whole width of the crystallizerI, which provides for a high quality of the slab ingot 7 being produced.By varying the rate of feed of the movable electrodes 3, it is possibleto regulate the total working current and the degree of immersion in theslag bath of the stationary electrodes 2. The main portion of metal isintroduced to the slab ingot 7 being produced by the stationaryelectrodes 2, while the movable electrodes 3 mainly serve to maintainand regulate the process of remelting. In order to reduce the length ofthe burnt-off portion of the movable electrodes 3, to the crystallizer 1in the course of melting, solid flux is added which while melting,increases the height of the slag bath 6, that is, displaces upwardly thesurface of the slag bath. Charging the solid flux in the course ofmelting makes for replacing the movable electrodes 3 withoutinterrupting the melting process since, at the moment of replacing theelectrodes 3, the melting process is maintained owing to the melting ofthe solid flux being charged. The amount of solid flux charged to thecrystallizer l in the course of melting should be such that, by the endof melting, the depth of the slag bath do not exceed the permissiblevalue, say, 1.5-2 times the width of the narrow face of thecrystallizer.

The hereinabove described method of producing slab ingots by way ofelectroslag remelting of consumable electrodes helps produce slab ingotsintended for direct sheet rolling without the use of powerful coggingmeans.

We claim:

1. A method of producing ingots, mainly slab ingots, by way ofelectroslag remelting of consumable electrodes, comprising introducingto a cooled crystallizer two groups of consumable electrodes connectedin series to the secondary winding of a single-phase transformer, eachof said groups of consumable electrodes comprising, parallelinterconnected, one electrode, stationary with respect to thecrystallizer and serving to introduce the main portion of metal to theslab ingot being produced, and at least one movable electrode serving tomaintain and regulate the process of remelting.

2. A method as set forth in claim I, wherein said movable consumableelectrodes are arranged in the crystallizer between said stationaryelectrodes.

3. A method as set forth in claim 1, wherein said movable electrodes arearranged in the crystallizer on the outer sides of said stationaryelectrodes.

4. A method as set forth in claim 1, wherein, with a view to increasingthe weight of the slab ingot without increasing the length of themovable electrodes, said movable electrodes are

1. A method of producing ingots, mainly slab ingots, by way ofelectroslag remelting of consumable electrodes, comprising introducingto a cooled crystallizer two groups of consumable electrodes connectedin series to the secondary winding of a single-phase transformer, eachof said groups of consumable electrodes comprising, parallelinterconnected, one electrode, stationary with respect to thecrystallizer and serving to introduce the main portion of metal to theslab ingot being produced, and at least one movable electrode serving tomaintain and regulate the process of remelting.
 2. A method as set forthin claim 1, wherein said movable consumable electrodes are arranged inthe crystallizer between said stationary electrodes.
 3. A method as setforth in claim 1, wherein said movable electrodes are arranged in thecrystallizer on the outer sides of said stationary electrodes.
 4. Amethod as set forth in claim 1, wherein, with a view to increasing theweight of the slab ingot without increasing the length of the movableelectrodes, said movable electrodes are replaced in the course ofremelting.
 5. A method as set forth in claim 1, further comprisingadding solid flux to said crystallizer during remelting, whereby thelength of the burnt-off portion of said movable electrodes may bereduced.